Developmental lead exposure induces tactile defensiveness in rhesus monkeys (Macaca mulatta).
BACKGROUND
Tactile defensiveness in children is associated with difficult social relations, emotional dysregulation, and inattention. However, there are no studies of lead exposure and tactile defensiveness in children or animals in spite of the fact that lead exposure is also associated with inattention and emotional dysregulation.


OBJECTIVE
In this study we tested whether lead exposure induces tactile defensiveness in rhesus monkeys.


METHODS
We tested 61 monkeys from a 3 (no lead, 1-year lead, 2-year lead) x 2 (succimer chelation or not) factorial experiment for tactile defensiveness at 4 years of age. Lead-treated monkeys had been orally administered lead in a daily milk solution from 8 days of life to either 1 or 2 years of age to produce blood lead levels of 35-40 mg/dL. Succimer chelation therapy or placebo was administered at 1 year of age. We measured tactile defensiveness using six repeated trials of each of three textures as a swipe to the cheek and neck.


RESULTS
Lead-exposed monkeys showed higher negative responses to repeated tactile stimulation compared with controls. Blood lead during the first 3 months of life was positively correlated with the negative response on the tactile defensiveness test. There was an interaction of lead exposure x succimer chelation x trials, but it is not clear that succimer chelation was beneficial with respect to tactile defensiveness.


CONCLUSIONS
This is the first report to implicate lead as a potential cause of tactile defensiveness. Research should examine whether lead exposure is associated with tactile defensiveness in children.
Moore
Colleen F
CF
Department of Psychology, University of Wisconsin-Madison, Madison, Wisconsin, USA.
Gajewski
Lisa L
LL
Laughlin
Nellie K
NK
Luck
Melissa L
ML
Larson
Julie A
JA
Schneider
Mary L
ML
D000818:Animals; D002614:Chelating Agents / Q000737:chemistry; D005260:Female; D007854:Lead / Q000737:chemistry / Q000633:toxicity*; D008253:Macaca mulatta; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D014110:Touch / Q000187:drug effects*
D002614:Chelating Agents; D007854:Lead